JPS63309844A - Inspecting device for nonmetallic inclusion - Google Patents

Abstract

PURPOSE:To discriminate a nonmetallic inclusion whose contained component is different, by converting an image obtained by magnifying it by a metallurgical microscope, of a nonmetallic inclusion to a multivalued video signal, and classifying the nonmetallic inclusion from a size and a luminance of the nonmetallic inclusion based on the video signal. CONSTITUTION:A high sensitivity TV camera 2 is attached to a metallurgical microscope 1, an image of an object to be inspected 9 is sent to an image input device 3, and in order to execute a multivalued processing, an 8-bit (256 gradations) processing is executed per one picture element. Subsequently, said image is converted to a digital signal by a transducer 4 and transferred to a nonmetallic inclusion classifying device 6. Subsequently, in the device 6, length and width of the inclusion are measured by executing a histogram processing in the vertical direction and the horizontal direction, an A1 compound (sulfide) inclusion is classified, a B compound inclusion is classified by measuring a distance between the inclusion and executing an array check, and from a ratio of length and width of the inclusion, it is classified into an A2 compound (sulfate) inclusion and a C compound inclusion, and a result of measurement is transmitted to a host computer 15. Accordingly, the nonmetallic inclusion can be discriminated, and by obviating a human error, the reliability can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an inspection device for nonmetallic inclusions to which image processing technology is applied.

[Conventional technology]

Microscopic nonmetallic inclusions are slightly mixed into steel materials during the manufacturing process of steel. The quality of steel materials is greatly affected by the composition, size, number, etc. of these nonmetallic inclusions, so we provide users with shipping inspection strategies, JIS (JI
SG-0555) and ASTM (ASTM-E4
5) Inspect non-metallic inclusions using a microscope as specified in 5). This inspection is usually performed visually by a person using an optical microscope, but in recent years, nonmetallic inclusion inspection devices that apply image processing technology have appeared. Regarding this device,
Metals (special issue.

(March 1980 issue), introduced by Kirishima Ayou.

[Problem that the invention seeks to solve]

Conventional nonmetallic inclusion inspection devices have a problem in that they cannot distinguish all the categories of nonmetallic inclusions listed in the JIS standard.

Figure 6 shows the classification of nonmetallic inclusions according to the JIS standard. There are A-based inclusions that are viscously deformed by processing, B-based inclusions that form a group in the processing direction and are discontinuously arranged in granular form, and C-based inclusions that do not undergo viscous deformation but are irregularly dispersed.

As shown in FIG. 6, these three types of inclusions can be classified if the shape of each inclusion and the distance between each inclusion are known, and therefore can be automatically classified using a conventional inspection device. However, in the case of inclusions of the same type, for example A-based inclusions, even if the shapes of the inclusions are the same, their compositions vary depending on their composition: Al-based sulfides, A2-based silicates, and A3-based composites.
It is necessary to classify it into a system. Conventional inspection devices do not have the ability to distinguish between these classifications.

[Means for solving problems]

The present invention advantageously solves the problems of the prior art, and provides a metallurgical microscope for magnifying non-metallic inclusions, and a television camera for converting images obtained from the metallurgical microscope into electrical signals. , an image input/output device including a converter that converts the electric signal into a multivalued video signal corresponding to the density of the screen, a memory that stores the video signal, and a non-metallic inclusion from the video signal. This is a nonmetallic inclusion inspection device characterized by comprising a device for measuring the dimensions of a nonmetallic inclusion and a nonmetallic inclusion classification device including a device for measuring the brightness of the nonmetallic inclusion.

Hereinafter, the configuration of the present invention will be described based on the drawings.

FIG. 1 is a configuration diagram of a nonmetallic inclusion inspection apparatus according to the present invention. The metallurgical microscope 1 magnifies nonmetallic inclusions, and uses an optical microscope, a scanning electron microscope, or the like. The television camera 2 converts images obtained from the metallurgical microscope 1 into electrical signals. The image input/output device 3 is
It includes a converter 4 that converts an electrical signal as a pixel into a multivalued video signal corresponding to the shading of an image, and a memory 5 that stores the video signal. If the multilevel level is 256 gradations (equivalent to 8 bits) from the black level to the white level, the size of the inclusion will be 25 μm x 5 as shown in Figure 2.
When micrometers or less are removed, the A-based inclusions can be separated into Al-based inclusions in sulfide and A2-based inclusions in silicate. The levels to be multivalued in this way have the same shape,
Used when classifying different contained components, 256 gradations (8
(bit) or higher is desirable. The non-metallic inclusion classification device 6 classifies non-metallic inclusions from the dimension measuring device 7 and the brightness measuring device 8 based on the multivalued image signal from the image input/output device 3.

〔Example〕

FIG. 3 shows the configuration of an apparatus for inspecting nonmetallic inclusions for high-grade wire rods, which is an embodiment of the present invention.

(1) Image input system A high-resolution TV left camera is attached to the metallurgical microscope 1, which has an automatic focus adjustment mechanism using an air backpressure system and an autostage mechanism driven by a step motor.

Therefore, once the operator determines the starting point on the object 9 to be inspected, the sample is automatically scanned to the point.

When inputting images to the image input/output device 3 using the TV left camera, it is natural to carefully select the image pickup tube.
By setting the vertical synchronization frequency of the system to 15 Hz due to hardware constraints, the bandwidth of the video signal is narrowed, the number of scanning lines is 1500, and a non-interlaced system is adopted.

The object to be inspected 9 has a rectangular shape of 5.5 mm x 11 mm, and the size of nonmetallic inclusions within the object to be inspected is several μm.
It is on the order of several tens of μm. The measurement accuracy is set to within 0.5 μm in standard deviation, and the field of view for image processing is 1428×1428 pixels per screen of a television camera, which is 242 screens per inspected object. Furthermore, 8-bit processing is performed per pixel in order to perform multi-value processing.

The image input system in FIG. 3 includes an auto stage and an auto focus mechanism 10. The autofocus controller 11 and the autostage controller 12 have an autofocus function to focus an image. The air source/air cleaner 13 is used to clean dust and the like from the object 9 to be inspected.

The vibration isolation table 14 prevents the image from being blurred even if there is some kind of vibration in the apparatus.

(2) In the image analysis system image input/output device 3, the signal from the TV camera is inputted here and converted to 1440 x 1440 x 8 by the converter 4.
It is converted into a bit digital signal and stored in the memory 5. The image data stored in the image input/output device 3 is transferred to the nonmetallic inclusion classification device 6, and the device M6 extracts the inclusion based on the magnitude of the inclusion and background signals.

The image data is divided into n parts in the scanning line direction by histogram processing as shown in FIG. 4, and a vertical histogram is obtained for each sector. From the vertical histogram, the locations of inclusions in each sector are extracted from Al, A2. A3. A4) Then, the vertical histogram of each sector is ORed for all sectors (B in FIG. 4).

Next, horizontal histograms are created in the order of areas (a), (b), and (c) (CI, C2, and C3 in FIG. 4). The obtained vertical histograms (AI, A2.A3.A4) and horizontal histograms (C1, C2, C3) are matched, and inclusions are labeled (1), (2), (3), and (4). The length, width, and coordinates of each inclusion are read.

Furthermore, the extracted inclusions are classified according to the magnitude of the signal according to the processing flow shown in FIG. There are three types of nonmetallic inclusions: A-based, B-based, and C-based, and A-based inclusions are AI-based (sulfide).

An example of classification into three types, A2 type (silicates) and A3 type (composite inclusions), a total of five types, is shown.

Image data showing non-metallic inclusions is first processed as multivalued capture (8 bits, 256 gradations). Then, vertical and horizontal histogram processing is performed to measure the length and width of the nonmetallic inclusion.

After that, first, Al
The inclusions are classified into A2-based, B-based, and C-based inclusions. Next, for inclusions other than At-based inclusions, the distance between each inclusion is measured to check the arrangement. If the distance (X, Y) between each inclusion is less than or equal to a predetermined value and there are n or more consecutive inclusions, the inclusions are classified as B-type inclusions. Next, the length to width ratio of the inclusion is determined, and if it is less than a standard value, it is classified as an A2 inclusion, and if it is more than the standard value, it is classified as a C type inclusion. In this way, the measurement results of the nonmetallic inclusion classification device are transmitted to the host computer 15.

〔Effect of the invention〕

According to the present invention, a nonmetallic inclusion inspection device can distinguish between nonmetallic inclusions that have the same shape but differ in content.Furthermore, the conventional problem of measurement error caused by humans is eliminated, and the quality of steel materials is guaranteed. This makes it possible to improve the reliability of the system.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of the apparatus of the present invention. FIG. 2 is a graph showing a histogram in which Al-based inclusions and A2-based inclusions are classified according to brightness level according to the present invention. FIG. 3 is a block diagram showing the configuration of an embodiment of the present invention. FIG. 4 is a front view showing an example of measuring the shape of a nonmetallic inclusion by the histogram processing of the present invention. FIG. 5 is a flowchart showing the process of classifying nonmetallic inclusions by the apparatus of the present invention. 1: Metallurgical microscope 2: Television camera 3: Image input/output device 4: Electrical signal multivalue processing converter 5: Memory 6: Nonmetallic inclusion classification device 7: Dimension measurement bag w 8: Luminance measurement device 9: Target Inspection object = 8-10 Niost stage, autofocus mechanism 11 Niost focus controller 12 Niost cheese controller 13: Near source/near purifier 14: Vibration isolation table 15: Host computer East 4
Diagram horizontal histoghum voice 5 diagram

Claims (1)

[Claims] A metallurgical microscope that magnifies nonmetallic inclusions, a television camera that converts images obtained from the metallurgical microscope into electrical signals,
An image input/output device including a converter that converts the electric signal into a multi-valued video signal corresponding to the density of the image, and a memory that stores the video signal; and a non-metallic inclusion size from the video signal. 1. A nonmetallic inclusion inspection device comprising: a nonmetallic inclusion classification device including a device for measuring brightness of the nonmetallic inclusions and a device for measuring the brightness of the nonmetallic inclusions.